This invention is concerned with far infra-red radiating materials made by using organometal compounds or organosilicon compounds.
Far infra-red rays can be described as infra-red rays with wavelengths in the region between 4-40 .mu.m. Far infra-red rays have a positive influence on living things and/or organic compounds because they are resonant with natural vibrations of all organic compounds which exist on the earth.
As the effects of far infra-red rays are discovered, ceramic materials which radiate far infra-red rays have been recently developed from natural and/or artificial minerals, and utilized in various fields.
Examples of primary substances used for making far infra-red radiating ceramic materials known so far are as follows:
1. Al.sub.2 O.sub.3 SiO.sub.2 (Japanese Patent Publication No. 78-44928);
2. ZrO.sub.2 , Y.sub.2 O.sub.3, La.sub.2 O.sub.3 CeO.sub.2 (Japanese Patent Laid-open No. 82-67073);
3. Fe.sub.2 O.sub.3, MgO, BaO (Japanese Patent Laid-Open No. 88-232268);
4. SnO.sub.2, Sb.sub.2 O.sub.3 (Japanese Patent Laid-Open No. 86-1755);
5. TiO.sub.2, CuO (Japanese Patent Laid-Open No. 85-251322).
The ceramic materials made by using the above described inorganic substances show relatively excellent radiation of far infra-red rays. Nevertheless, the utilization of them are rather restricted because of their high specific gravities, inferior transparencies, and weak intimacies with base materials.